Great Plains NH3 Safety - Manual (Page 18)

14 NH
3
Safety Table of Contents Index Great Plains Manufacturing, Inc.
407-551M Table of Contents Index 2013-07-15
Refer to Figure 9 (depicting a hydrostatic relief valve, with a
bleed valve for scale)
A63 Hydrostatic Relief Valve:
Hydrostatic relief valves may be found at multiple
locations, typically anywhere that NH
3
could be
trapped (such as in a dual-valve hose).
These are usually identified by a black polymer cap.
If the cap is missing, the valve may have been
activated at some time.
Hydrostatic relief valves are designed to open at
pressures higher than the nurse tank pressure relief
valve
(page 18, 250-265 psi). Normal excess
pressure vents at the nurse tank pressure relief
valve. A release at a hydrostatic relief valve
indicates a malfunction or operator error.
Hydrostatic relief valves are usually limited-life
components.
Nurse Tank Forward Fittings
Refer to Figure 10 and Figure 11
A welded roll cage, normally located at the top front of
the tank, contains all the operating and status fittings
except the relief valve (
, page 21), and the drain valve
( , page 21).
Decals on the tank or protective structure may identify
the valves and fittings. Valves may be color-coded. Make
sure all operators know where each valve or fitting is
located. Several of the valves have a similar mechanical
appearance.
As the tank operator, you will operate one of these
fittings (the withdrawal valve
), and periodically check
two others (the pressure and float gauges).
You need to know the functions of all of the fittings in this
group for purposes of tank inspection and acceptance.
Figure 9
Hydrostatic Relief Valve
31564
A63
A80
Figure 10
Nurse Tank Forward Fittings
31560
}
A80
A79
A66
A68 A71